Linux: Code: ln -s /path/to/full/directory/of/players /path/to/server2/directory If your server is hosted on a Windows system, check this.
That's bad. You are very limited to stuff that you can do. Buy a VPS/Dedicated server. I don't think you can get the best solutions while you're using multicraft. Just my two cents...
Yes but you'll have to save the gzip-compressed (NBT) inventory into mysql. (You can refer to this code to check how I did that). You'll also have to fetch the inventory from mysql every time the player logs in. (Both the tasks should be done asynchronously, or expect a ton of lag o/). So the better option is to link folders.